Growth and body composition of periurban Guatemalan children in relation to zinc status: a longitudinal zinc intervention trial.

Changes in growth, body composition, and zinc indexes were evaluated after 25 wk in a double-blind zinc-supplementation study of 162 periurban Guatemalan children aged 81.5 +/- 7.0 mo (mean +/- SD). Children receiving the zinc supplement (10 mg Zn/d as amino acid chelate) for 90.1 +/- 9.2 d had higher mean fasting plasma zinc (16.2 +/- 2.9 vs 14.9 +/- 2.1 mumol/L, P < 0.01), a greater increase in median triceps skinfold Z score (0.50 vs 0.38, P < 0.05), and a smaller deficit in median midarm circumference (MAC) Z score (-0.03 vs -0.20, P < 0.05) compared with the placebo group. Initial hair zinc classified as < 1.68 and > 1.68 mumol/g was the only laboratory variable that explained some of the variance in final Z scores of midarm-muscle area (P < 0.05) and MAC (P < 0.01). Children responded to the zinc supplement with changes in indexes of body composition rather than growth.

Erythrocytes, erythrocyte membranes, neutrophils and platelets as biopsy materials for the assessment of zinc status in humans.

During a controlled zinc depletion-repletion study, fifteen men aged 25.3 (SD 3.3) years were fed on a low-Zn diet with high phytate:Zn and phytate x calcium:Zn molar ratios for 7 weeks, followed by a 2 week repletion period when 30 mg supplemental Zn/d was given. Changes in plasma, urine, and hair Zn concentrations, taste acuity, and cellular immune response confirmed the development of mild Zn deficiency. Zn concentrations in neutrophils, platelets, erythrocytes and erythrocyte membranes, mean platelet volume, and activities of alkaline phosphatase (EC 3.1.3.1) and alpha-D-mannosidase (EC 3.2.1.24) in neutrophils did not respond to changes in Zn status. In contrast, alkaline phosphatase activity in erythrocyte membranes showed a significant decline which was consistent in all subjects (nmol product formed/min per mg protein; baseline v. 7-week Zn depletion, 0.656 (SD 0.279) v. 0.506 (SD 0.230), at 7 weeks; P < 0.05); neutral phosphatase activity remained unchanged. Alkaline phosphatase activity in erythrocyte membranes may be a potential index of Zn status in humans.

Potential for dietary amino acid precursors of neurotransmitters to overcome neurochemical changes in acute T-2 toxicosis in rats.

Experiments were conducted to determine the potential for overcoming T-2 toxin-induced changes in brain neurotransmitter concentrations through dietary manipulation. Rats were fed either a tryptophan-deficient, gelatin-based diet or the same diet supplemented with a mixture of large neutral amino acids for 4 d. Rats were then dosed with 0 or 2.0 mg T-2 toxin/kg body weight and killed 4, 8 or 12 h after dosing. The large neutral amino acid supplements successfully reduced brain concentrations of tryptophan and serotonin in control rats, but this was not enough to overcome the acute effects seen in T-2 toxin-treated rats. A further experiment was then conducted to monitor the effect of T-2 toxin on the ratio of free to protein-bound tryptophan in plasma. Total plasma tryptophan increased in T-2 toxin-treated rats, although there were no significant differences in the ratio of free to protein-bound tryptophan. A final experiment was conducted to determine the specificity of the T-2 toxin effect on concentrations of plasma amino acids. Concentrations of amino acids that use the large neutral amino acid transport system into the brain were higher in T-2 toxin-treated animals. The only other amino acid that had a higher concentration was arginine. It was concluded that acute doses of T-2 toxin may selectively alter membrane transport of amino acids.